Legal Gap or Compliance Gap?

October 2015

Beatrice Fihn’s recent article (“A New Humanitarian Era: Prohibiting the Unacceptable,” July/August 2015) highlights the commitment by the signers of the “Humanitarian Pledge” to “pursue effective measures to fill the legal gap for the prohibition and elimination of nuclear weapons.” Put forward by Austria in December 2014, the pledge is now supported by well more than 100 countries. Fihn also states, rightly, that nuclear weapons “fundamentally violate the principles of humanitarian law.”

If the use of nuclear weapons already is unlawful, how should the concept of a “legal gap” be understood? The deficiency should be seen as a compliance gap, the failure to eliminate nuclear weapons in accordance with Article VI of the nuclear Nonproliferation Treaty (NPT). That article requires the pursuit of negotiations in good faith of “effective measures…relating to nuclear disarmament.”

Paul Dean (“The Role of Negotiation in International Arms Control Law,” September 2015) convincingly develops the obvious but essential point that nuclear-armed states must participate in negotiations of legal instruments if disarmament is to be effective. We made similar arguments in an April 2015 paper of the International Association of Lawyers Against Nuclear Arms, “Nuclear Disarmament: The Road Ahead.”

Dean goes astray, however, by contending 45 years after the NPT entered into force that U.S. pursuit of partial measures such as a fissile material cutoff treaty, coupled with systematic opposition to commencement of multilateral negotiations on elimination of nuclear arsenals, suffices to comply with Article VI. The NPT was never intended to be a license for the indefinite possession of nuclear arms by the NPT-acknowledged nuclear-weapon states.

Furthermore, the concept of a legal gap should not be understood as in any way signaling that the use of nuclear weapons is currently legally permissible. Nuclear weapons simply cannot be used in compliance with fundamental principles of international law protecting civilians from the effects of warfare, protecting combatants from unnecessary suffering, and protecting the natural environment. The International Committee of the Red Cross has recently confirmed this analysis. Although, as Dean notes, a 1996 advisory opinion of the International Court of Justice did not find the use of nuclear weapons to be categorically illegal, the thrust of the opinion is that nuclear weapons cannot be used in compliance with the above principles. In many circumstances, use of nuclear weapons would constitute a crime against humanity as defined in the Rome Statute of the International Criminal Court.

The nuclear-armed states and their allies have not accepted this legal truth. That is illustrated by Dean’s assertion that whether a use of nuclear weapons is legal would depend on the circumstances and by the Law of War Manual released in June 2015 by the U.S. Department of Defense. While acknowledging that the “law of war governs the use of nuclear weapons,” the manual maintains that because the “United States has not accepted a treaty rule that prohibits the use of nuclear weapons per se,…nuclear weapons are lawful weapons for the United States.” The lack of serious analysis of use of nuclear weapons under existing law places the Defense Department at odds with U.S. courts, from the Supreme Court on down, which have consistently affirmed the reality and enforceability of customary—that is, nontreaty—international law.

A treaty prohibition on use of nuclear weapons in any circumstance would codify the existing illegality of their use. That is the way law generally develops, from common law to statutory law, from custom to treaty. By joining such a treaty, nuclear-armed and nuclear-umbrella states would unequivocally accept the illegality of use. For these reasons, an explicit prohibition of use should be included in the legal measures negotiated to fill the compliance gap. In the meantime, however, supporters of the Humanitarian Pledge should stress that the use of nuclear weapons already is unlawful.